UK Vintage Radio Repair and Restoration Discussion Forum - View Single Post - 5FP7 project starting with the focusing coil.

Graham G3ZVT · 14th Oct 2021, 10:42 pm

Hi Adrian , I built an SSTV monitor based on a 5FP7 45 years ago.
If I remember correctly the EHT generator was EF80 osc into a 6BW6 driving a Thorn 1500 Jelypot with an EHT tray that I think was a doubler. The rest of the circuit was solid-state, the time-bases were 741 driving a TIP41/TIP42 pair. I'm sure I over did the EHT voltage and flashovers regularly did for one or both 741s!

The scan coils came out of a 1950s TV and as there was no focus coil, I must have used a permanent magnet, probably out of the same TV, the focus was very good.

Those 5FP7s are versatile things, with a blue filter over the screen, its raster has a short enough persistence to make make a passable flying-spot scanner, I did some SSTV and fast scan experiments with a 921A PM tube.

14th Oct 2021, 10:42 pm	#17
Graham G3ZVT Dekatron Join Date: May 2010 Location: Greater Manchester, UK. Posts: 18,713	Re: 5FP7 project starting with the focusing coil. Hi Adrian , I built an SSTV monitor based on a 5FP7 45 years ago. If I remember correctly the EHT generator was EF80 osc into a 6BW6 driving a Thorn 1500 Jelypot with an EHT tray that I think was a doubler. The rest of the circuit was solid-state, the time-bases were 741 driving a TIP41/TIP42 pair. I'm sure I over did the EHT voltage and flashovers regularly did for one or both 741s! The scan coils came out of a 1950s TV and as there was no focus coil, I must have used a permanent magnet, probably out of the same TV, the focus was very good. Those 5FP7s are versatile things, with a blue filter over the screen, its raster has a short enough persistence to make make a passable flying-spot scanner, I did some SSTV and fast scan experiments with a 921A PM tube. __________________ -- Graham. G3ZVT Last edited by Graham G3ZVT; 14th Oct 2021 at 10:59 pm.